How to create cotton wool?
I've tried this, I think it needs more hair work though, to get the fluffy thing. For the material, I've used a Noise Texture that I've scaled on one axis to get the stria effect. Emission is here to give a bit of luminosity and softness to the object, too much shadow would make it look solid like a stone, it somehow simulates a transparent effect. And at the end a bit of Transparency, with a Fresnel as factor, to make the contour a bit evanescent. The hairs are actually long extruded rectangles with a material that also use a mix of Diffuse, Emission and Transparency.